---
title: "Peptide Purity Test vs Identity Test: The Difference"
url: https://www.primaralabs.com/answers/purity-vs-identity-testing
source: Primara Labs, markdown mirror of the HTML page
---

# What is the difference between a purity test and an identity test?

An identity test checks that a vial holds the compound named on the label; a purity test, usually by HPLC, measures what share of the detected material is that compound. As of 23 September 2026, laboratories sell them together because each is incomplete alone: a pure sample of the wrong peptide passes purity.

Updated 23 September 2026

01

## The two tests

An identity test checks that the substance is the compound named. Mass spectrometry measures the molecule's mass directly; an HPLC identity check compares how long the sample takes to pass through a column against a reference standard, which is weaker evidence on its own.

A purity result, usually by HPLC, is the share of the detected material that is the target compound. It does not by itself prove what that compound is, which is why purity is normally paired with an identity test.

A quantity result states how much of the compound the vial holds, usually in milligrams. A vial can be pure and still hold less than its label says.

02

## How laboratories bundle them

Janoshik Analytical's single-compound analyses cover identity, purity and amount; for example "BPC-157 analysis" at US$215. Accepts samples from anywhere in the world, per its own site. Its only test labelled blind is the common GLP-1 blind test. Blend analyses measure identity and amount but not purity.

Accumark Labs lists "Core Panel (Identity, Purity & Quantity)" at US$250. States US sample intake. Identity is by HPLC; LC-MS identity is listed as in development. No sample quantity is stated.

03

## What to read on the report

What the test covers: An endotoxin test says nothing about identity or purity; an identity test says nothing about endotoxin. Read the tests requested line.

The figure and its unit: The result should match what the seller quotes, in the same unit. Per vial, per mg and per mL are not interchangeable.

Sources

## Where every figure comes from

1.  [Janoshik Analytical, price list](https://janoshik.com/c/peptides/) · checked 23 September 2026
2.  [Accumark Labs, price list](https://accumarklabs.com/services/) · checked 23 September 2026
3.  [Primara COA Reader, test explainers](https://www.primaralabs.com/tools/coa-reader) · checked 23 September 2026

Last reviewed 23 September 2026

Read next

## Related pages

-   [COA Reader](https://www.primaralabs.com/tools/coa-reader)
-   [Lab Test Planner](https://www.primaralabs.com/tools/lab-test-planner)

-   [What is a blind peptide test?](https://www.primaralabs.com/answers/what-is-a-blind-peptide-test)
-   [What does an endotoxin result on a peptide vial mean?](https://www.primaralabs.com/answers/what-does-an-endotoxin-result-mean)